Buttigieg, a Democrat who served under President Biden, made the case in an interview with NPR's Leila Fadel. He pushed back on the Trump administration's claim that loosening the standards will make cars cheaper for buyers.
The Transportation Department argues the new rules could cut the price of a new vehicle by about $1,300. But the agency's own estimate says drivers could end up paying roughly $1,600 more in fuel costs over the life of that same vehicle. Buttigieg said that number does not fully capture the risk of higher gas prices or the impact of tariffs on the auto industry.
For drivers, the math matters. A lower sticker price sounds good at the dealership, but if fuel costs eat up the savings and then some, the deal looks different once the car is on the road for years.
Buttigieg's broader worry goes beyond any one buyer's gas bill. He argued that weaker fuel-economy rules could leave U.S. Automakers falling further behind Chinese competitors already pushing hard on efficiency and electric vehicles.